drivers/gpio/gpio-syscon.c

   1 /*
   2  *  SYSCON GPIO driver
   3  *
   4  *  Copyright (C) 2014 Alexander Shiyan <shc_work@mail.ru>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  */
  11
  12 #include <linux/err.h>
  13 #include <linux/gpio.h>
  14 #include <linux/module.h>
  15 #include <linux/of.h>
  16 #include <linux/of_device.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/regmap.h>
  19 #include <linux/mfd/syscon.h>
  20
  21 #define GPIO_SYSCON_FEAT_IN     BIT(0)
  22 #define GPIO_SYSCON_FEAT_OUT    BIT(1)
  23 #define GPIO_SYSCON_FEAT_DIR    BIT(2)
  24
  25 /* SYSCON driver is designed to use 32-bit wide registers */
  26 #define SYSCON_REG_SIZE         (4)
  27 #define SYSCON_REG_BITS         (SYSCON_REG_SIZE * 8)
  28
  29 /**
  30  * struct syscon_gpio_data - Configuration for the device.
  31  * compatible:          SYSCON driver compatible string.
  32  * flags:               Set of GPIO_SYSCON_FEAT_ flags:
  33  *                      GPIO_SYSCON_FEAT_IN:    GPIOs supports input,
  34  *                      GPIO_SYSCON_FEAT_OUT:   GPIOs supports output,
  35  *                      GPIO_SYSCON_FEAT_DIR:   GPIOs supports switch direction.
  36  * bit_count:           Number of bits used as GPIOs.
  37  * dat_bit_offset:      Offset (in bits) to the first GPIO bit.
  38  * dir_bit_offset:      Optional offset (in bits) to the first bit to switch
  39  *                      GPIO direction (Used with GPIO_SYSCON_FEAT_DIR flag).
  40  */
  41
  42 struct syscon_gpio_data {
  43         const char      *compatible;
  44         unsigned int    flags;
  45         unsigned int    bit_count;
  46         unsigned int    dat_bit_offset;
  47         unsigned int    dir_bit_offset;
  48 };
  49
  50 struct syscon_gpio_priv {
  51         struct gpio_chip                chip;
  52         struct regmap                   *syscon;
  53         const struct syscon_gpio_data   *data;
  54 };
  55
  56 static inline struct syscon_gpio_priv *to_syscon_gpio(struct gpio_chip *chip)
  57 {
  58         return container_of(chip, struct syscon_gpio_priv, chip);
  59 }
  60
  61 static int syscon_gpio_get(struct gpio_chip *chip, unsigned offset)
  62 {
  63         struct syscon_gpio_priv *priv = to_syscon_gpio(chip);
  64         unsigned int val, offs = priv->data->dat_bit_offset + offset;
  65         int ret;
  66
  67         ret = regmap_read(priv->syscon,
  68                           (offs / SYSCON_REG_BITS) * SYSCON_REG_SIZE, &val);
  69         if (ret)
  70                 return ret;
  71
  72         return !!(val & BIT(offs % SYSCON_REG_BITS));
  73 }
  74
  75 static void syscon_gpio_set(struct gpio_chip *chip, unsigned offset, int val)
  76 {
  77         struct syscon_gpio_priv *priv = to_syscon_gpio(chip);
  78         unsigned int offs = priv->data->dat_bit_offset + offset;
  79
  80         regmap_update_bits(priv->syscon,
  81                            (offs / SYSCON_REG_BITS) * SYSCON_REG_SIZE,
  82                            BIT(offs % SYSCON_REG_BITS),
  83                            val ? BIT(offs % SYSCON_REG_BITS) : 0);
  84 }
  85
  86 static int syscon_gpio_dir_in(struct gpio_chip *chip, unsigned offset)
  87 {
  88         struct syscon_gpio_priv *priv = to_syscon_gpio(chip);
  89
  90         if (priv->data->flags & GPIO_SYSCON_FEAT_DIR) {
  91                 unsigned int offs = priv->data->dir_bit_offset + offset;
  92
  93                 regmap_update_bits(priv->syscon,
  94                                    (offs / SYSCON_REG_BITS) * SYSCON_REG_SIZE,
  95                                    BIT(offs % SYSCON_REG_BITS), 0);
  96         }
  97
  98         return 0;
  99 }
 100
 101 static int syscon_gpio_dir_out(struct gpio_chip *chip, unsigned offset, int val)
 102 {
 103         struct syscon_gpio_priv *priv = to_syscon_gpio(chip);
 104
 105         if (priv->data->flags & GPIO_SYSCON_FEAT_DIR) {
 106                 unsigned int offs = priv->data->dir_bit_offset + offset;
 107
 108                 regmap_update_bits(priv->syscon,
 109                                    (offs / SYSCON_REG_BITS) * SYSCON_REG_SIZE,
 110                                    BIT(offs % SYSCON_REG_BITS),
 111                                    BIT(offs % SYSCON_REG_BITS));
 112         }
 113
 114         syscon_gpio_set(chip, offset, val);
 115
 116         return 0;
 117 }
 118
 119 static const struct syscon_gpio_data clps711x_mctrl_gpio = {
 120         /* ARM CLPS711X SYSFLG1 Bits 8-10 */
 121         .compatible     = "cirrus,clps711x-syscon1",
 122         .flags          = GPIO_SYSCON_FEAT_IN,
 123         .bit_count      = 3,
 124         .dat_bit_offset = 0x40 * 8 + 8,
 125 };
 126
 127 static const struct of_device_id syscon_gpio_ids[] = {
 128         {
 129                 .compatible     = "cirrus,clps711x-mctrl-gpio",
 130                 .data           = &clps711x_mctrl_gpio,
 131         },
 132         { }
 133 };
 134 MODULE_DEVICE_TABLE(of, syscon_gpio_ids);
 135
 136 static int syscon_gpio_probe(struct platform_device *pdev)
 137 {
 138         struct device *dev = &pdev->dev;
 139         const struct of_device_id *of_id = of_match_device(syscon_gpio_ids, dev);
 140         struct syscon_gpio_priv *priv;
 141
 142         priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 143         if (!priv)
 144                 return -ENOMEM;
 145
 146         priv->data = of_id->data;
 147
 148         priv->syscon =
 149                 syscon_regmap_lookup_by_compatible(priv->data->compatible);
 150         if (IS_ERR(priv->syscon))
 151                 return PTR_ERR(priv->syscon);
 152
 153         priv->chip.dev = dev;
 154         priv->chip.owner = THIS_MODULE;
 155         priv->chip.label = dev_name(dev);
 156         priv->chip.base = -1;
 157         priv->chip.ngpio = priv->data->bit_count;
 158         priv->chip.get = syscon_gpio_get;
 159         if (priv->data->flags & GPIO_SYSCON_FEAT_IN)
 160                 priv->chip.direction_input = syscon_gpio_dir_in;
 161         if (priv->data->flags & GPIO_SYSCON_FEAT_OUT) {
 162                 priv->chip.set = syscon_gpio_set;
 163                 priv->chip.direction_output = syscon_gpio_dir_out;
 164         }
 165
 166         platform_set_drvdata(pdev, priv);
 167
 168         return gpiochip_add(&priv->chip);
 169 }
 170
 171 static int syscon_gpio_remove(struct platform_device *pdev)
 172 {
 173         struct syscon_gpio_priv *priv = platform_get_drvdata(pdev);
 174
 175         gpiochip_remove(&priv->chip);
 176         return 0;
 177 }
 178
 179 static struct platform_driver syscon_gpio_driver = {
 180         .driver = {
 181                 .name           = "gpio-syscon",
 182                 .owner          = THIS_MODULE,
 183                 .of_match_table = syscon_gpio_ids,
 184         },
 185         .probe  = syscon_gpio_probe,
 186         .remove = syscon_gpio_remove,
 187 };
 188 module_platform_driver(syscon_gpio_driver);
 189
 190 MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
 191 MODULE_DESCRIPTION("SYSCON GPIO driver");
 192 MODULE_LICENSE("GPL");